[FieldTrip] Cluster-based permutation test with different sample sizes by channel

[Soren Emmanuel Wainio-Theberge]

Hello all,

My name is Soren Wainio-Theberge, and I'm working in the Mind, Brain
Imaging and Neuroethics unit in Ottawa, Canada. I had a question about
using cluster-based permutation tests with my data. I'm working with a
large ECoG dataset, and I've grouped all the electrodes into regions
according to an atlas. I wanted to do a cluster-based permutation test on
the region-based results (since I have reason to suspect region-specific
effects, but don't want to go as far as specifying a priori ROIs). However,
since this is ECoG data each subject has only a subset of the full number
of regions represented, depending on their electrode placement. As such,
each region will have a different sample size. At the moment I'm only
clustering across channels, not across time or time-frequency.

My fix was to permute each channel separately, rather than all together,
which seems to work code-wise. My question is whether this a statistically
sound thing to do - is the cluster test sensitive to differences in sample
size for each region?

Best and thanks very much,
Soren Wainio-Theberge
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mailman.science.ru.nl/pipermail/fieldtrip/attachments/20190523/50f32e7d/attachment-0001.html>
-------------- next part --------------
_______________________________________________
fieldtrip mailing list
https://mailman.science.ru.nl/mailman/listinfo/fieldtrip
https://doi.org/10.1371/journal.pcbi.1002202